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Ebola expert answers your questions

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The Ebola virus kills up to 90% of people who catch it, according to Medecins Sans Frontieres

How is it transmitted? Is there any treatment? Can we protect ourselves?

We address some of your most frequently asked questions about the disease

The largest Ebola outbreak in history has struck fear into the hearts of people around the world. While fewer than 3,000 people have been killed by the virus since it was discovered in 1976, the disease's virulence and deadliness, combined with the lack of a cure, inspire dread like almost no other.

We asked you what questions you had about Ebola and received more than 1,000 responses via social media. Here are expert answers to some of your most common questions and concerns.

The virus is named after the Ebola River in the Democratic Republic of Congo (formerly Zaire), where one of the first outbreaks occurred in 1976.

The World Health Organization says there are five different strains of the virus, named after the areas where they originated. Three of these have been associated with large outbreaks of hemorrhagic fever in Africa. Of Ebola's five subtypes, the Zaire strain -- the first to be identified -- is considered the most deadly. The WHO said preliminary tests on the Ebola virus in Guinea in March suggested that the outbreak there was this strain, though that has not been confirmed.

What are Ebola's symptoms?

Early symptoms include sudden onset of fever, weakness, muscle pain, headaches and a sore throat. These symptoms can appear two to 21 days after infection.

The WHO says these nonspecific early symptoms can be mistaken for signs of diseases such as malaria, typhoid fever, meningitis or even the plague.

MSF says some patients may also develop a rash, red eyes, hiccups, chest pains and difficulty breathing and swallowing.

The early symptoms progress to vomiting, diarrhea, impaired kidney and liver function and sometimes internal and external bleeding. CNN's Dr. Sanjay Gupta says that if a patient is going to die from Ebola, he or she usually does so within about 10 days.

Ebola can only be definitively confirmed by five different laboratory tests.

How is it treated? What about that experimental drug?

There are no specific approved treatments for Ebola. MSF says patients are isolated and then supported by health care workers.

"This consists of hydrating the patient, maintaining their oxygen status and blood pressure and treating them for any complicating infections," it says.

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Life in Liberia during the Ebola outbreak03:21

Photos:The Ebola epidemic

Photos:The Ebola epidemic

An Ebola survivor participates in a study in Monrovia, Liberia, on June 17. The country launched a five-year study to unravel the mystery of the long-term health effects that plague survivors of the viral disease. Since the epidemic started more than a year ago in a remote village in Guinea, more than 11,000 people have died, the vast majority in three West African nations, according to the latest numbers from the World Health Organization. And that number is believed to be low, since there was widespread under-reporting of cases, according to WHO.

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Women in Monrovia celebrate after the World Health Organization declared Liberia Ebola-free on May 9. Other cases have recurred since, however. Two people in Liberia have died of the disease since the end of June, just weeks after the WHO declared the nation free of the disease.

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A man walks past an Ebola awareness painting in Monrovia on March 22.

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Soldiers from the U.S. Army's 101st Airborne Division walk across the tarmac at Campbell Army Airfield before reuniting with their families at a homecoming ceremony March 21 in Fort Campbell, Kentucky. The 162 soldiers were deployed in Liberia, where they helped fight the spread of Ebola.

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Relatives weep for a loved one who it was believed died from Ebola, at a graveyard on the outskirts of Monrovia on March 11.

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Doctors Without Borders staffer Alex Eilert Paulsen watches as mattresses and bed frames burn at the Ebola Treatment Unit in Paynesville, Liberia, on January 31. The organization reduced its number of beds from 250 to 30 as gains were made in battling the virus.

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Pauline Cafferkey, a Scottish woman diagnosed with Ebola, is put on a plane in Glasgow, Scotland, on December 30, 2014. Cafferkey, a 39-year-old nurse who volunteered in Sierra Leone, was being transported to London for treatment.

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A child who survived the Ebola virus is fed by another survivor at a treatment center on the outskirts of Freetown, Sierra Leone, on November 11, 2014.

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Health workers in Monrovia cover the body of a man suspected of dying from the Ebola virus on October 31, 2014.

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Kaci Hickox leaves her home in Fort Kent, Maine, to take a bike ride with her boyfriend on October 30, 2014. Hickox, a nurse, recently returned to the United States from West Africa, where she treated Ebola victims. State authorities wanted her to avoid public places for 21 days -- the virus' incubation period. But Hickox, who twice tested negative for Ebola, said she would defy efforts to keep her quarantined at home.

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Health officials in Nairobi, Kenya, prepare to screen passengers arriving at the Jomo Kenyatta International Airport on October 28, 2014.

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U.S. President Barack Obama hugs Ebola survivor Nina Pham in the Oval Office of the White House on October 24, 2014. Pham, one of two Dallas nurses diagnosed with the virus, was declared Ebola-free after being treated at a hospital in Bethesda, Maryland. The other nurse, Amber Vinson (not pictured), was treated in Atlanta and also declared Ebola-free.

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Health workers in Port Loko, Sierra Leone, transport the body of a person who is suspected to have died of Ebola on October 21, 2014.

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Health workers bury a body on the outskirts of Monrovia on October 20, 2014.

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Garteh Korkoryah, center, is comforted during a memorial service for her son, Thomas Eric Duncan, on October 18, 2014, in Salisbury, North Carolina. Duncan, a 42-year-old Liberian citizen, died October 8 in a Dallas hospital. He was in the country to visit his son and his son's mother, and he was the first person in the United States to be diagnosed with Ebola.

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Boys run from blowing dust as a U.S. military aircraft leaves the construction site of an Ebola treatment center in Tubmanburg, Liberia, on October 15, 2014.

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Aid workers from the Liberian Medical Renaissance League stage an Ebola awareness event October 15, 2014, in Monrovia. The group performs street dramas throughout Monrovia to educate the public on Ebola symptoms and how to handle people who are infected with the virus.

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Ebola survivors prepare to leave a Doctors Without Borders treatment center after recovering from the virus in Paynesville, Liberia, on October 12, 2014.

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A man dressed in protective clothing treats the front porch of a Dallas apartment on October 12, 2014. The apartment is home to one of the two nurses who were diagnosed with Ebola after treating Thomas Eric Duncan, a Liberian national who traveled to Dallas and later died from the virus.

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A woman crawls toward the body of her sister as a burial team takes her away for cremation October 10, 2014, in Monrovia. The sister had died from Ebola earlier in the morning while trying to walk to a treatment center, according to her relatives.

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A man digs a grave on October 7, 2014, outside an Ebola treatment center near Gbarnga, Liberia.

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A person peeks out from the Dallas apartment where Thomas Eric Duncan, the first person diagnosed with the Ebola virus in the United States, was staying on October 3, 2014.

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A girl cries as community activists approach her outside her Monrovia home on October 2, 2014, a day after her mother was taken to an Ebola ward.

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A health official uses a thermometer September 29, 2014, to screen a Ukrainian crew member on the deck of a cargo ship at the Apapa port in Lagos, Nigeria.

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Workers move a building into place as part of a new Ebola treatment center in Monrovia on September 28, 2014.

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Medics load an Ebola patient onto a plane at Sierra Leone's Freetown-Lungi International Airport on September 22, 2014.

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A few people are seen in Freetown during a three-day nationwide lockdown on September 21, 2014. In an attempt to curb the spread of the Ebola virus, people in Sierra Leone were told to stay in their homes.

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Supplies wait to be loaded onto an aircraft at New York's John F. Kennedy International Airport on September 20, 2014. It was the largest single shipment of aid to the Ebola zone to date, and it was coordinated by the Clinton Global Initiative and other U.S. aid organizations.

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A child stops on a Monrovia street September 12, 2014, to look at a man who is suspected of suffering from Ebola.

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After an Ebola case was confirmed in Senegal, people load cars with household items as they prepare to cross into Guinea from the border town of Diaobe, Senegal, on September 3, 2014.

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A health worker wearing a protective suit conducts an Ebola prevention drill at the port in Monrovia on August 29, 2014.

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A burial team from the Liberian Ministry of Health unloads bodies of Ebola victims onto a funeral pyre at a crematorium in Marshall, Liberia, on August 22, 2014.

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Dr. Kent Brantly leaves Emory University Hospital on August 21, 2014, after being declared no longer infectious from the Ebola virus. Brantly was one of two American missionaries brought to Emory for treatment of the deadly virus.

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An Ebola Task Force soldier beats a local resident while enforcing a quarantine on the West Point slum on August 20, 2014.

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Local residents gather around a very sick Saah Exco, 10, in a back alley of the West Point slum on August 19, 2014. The boy was one of the patients that was pulled out of a holding center for suspected Ebola patients after the facility was overrun and closed by a mob on August 16. A local clinic then refused to treat Saah, according to residents, because of the danger of infection. Although he was never tested for Ebola, Saah's mother and brother died in the holding center.

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Workers prepare the new Ebola treatment center on August 17, 2014.

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Liberian police depart after firing shots in the air while trying to protect an Ebola burial team in the West Point slum of Monrovia on August 16, 2014. A crowd of several hundred local residents reportedly drove away the burial team and their police escort. The mob then forced open an Ebola isolation ward and took patients out, saying the Ebola epidemic is a hoax.

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A health worker disinfects a corpse after a man died in a classroom being used as an Ebola isolation ward August 15, 2014, in Monrovia.

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Aid worker Nancy Writebol, wearing a protective suit, gets wheeled on a gurney into Emory University Hospital in Atlanta on August 5, 2014. A medical plane flew Writebol from Liberia to the United States after she and her colleague Dr. Kent Brantly were infected with the Ebola virus in the West African country.

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Members of Doctors Without Borders adjust tents in the isolation area in Kailahun on July 20, 2014.

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Boots dry in the Ebola treatment center in Kailahun on July 20, 2014.

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Dr. Jose Rovira of the World Health Organization takes a swab from a suspected Ebola victim in Pendembu, Sierra Leone, on July 18, 2014.

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Red Cross volunteers disinfect each other with chlorine after removing the body of an Ebola victim from a house in Pendembu on July 18, 2014.

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A scientist separates blood cells from plasma cells to isolate any Ebola RNA and test for the virus April 3, 2014, at the European Mobile Laboratory in Gueckedou, Guinea.

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Health specialists work March 31, 2014, at an isolation ward for patients at the facility in southern Guinea.

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Cost of containing Ebola on the rise07:08

Two American missionary workers infected with Ebola were given an experimental drug called ZMapp, which seems to have saved their lives. The drug, developed by a San Diego firm, had never been tried before on humans, but it showed promise in small experiments on monkeys. The Americans who received it have since been declared healthy and discharged from Emory University Hospital in Atlanta.

ZMapp was also administered to three Liberian health care workers who contracted Ebola. At first, they showed "very positive signs of recovery," according to the Liberian Ministry of Health, but one has since died of the disease.

Why haven't other patients been given the experimental drug?

An ethics panel convened by the WHO concluded it is ethical to give experimental drugs during an outbreak as large as this one, but that doesn't mean it will happen.

Rolling out an untested drug during a massive outbreak would be very difficult, according to MSF. Experimental drugs are typically not mass-produced, and tracking the success of such a drug if used would require extra medical staff where resources are already scarce. ZMapp's maker says it has very few doses ready for patient use.

What about a vaccine?

There is currently no approved vaccination against Ebola.

At least one potential Ebola vaccine has been tested in healthy human volunteers, according to Thomas Geisbert, a leading researcher at the University of Texas Medical Branch. And last week, the NIH announced that a safety trial of another Ebola vaccine will start as early as September.

In March, the U.S. National Institutes of Health awarded a five-year, $28 million grant to establish a collaboration between researchers from 15 institutions who were working to fight Ebola.

Humans contract Ebola through contact with the bodily fluids of infected animals or the bodily fluids of infected humans, like blood, sweat and feces.

MSF epidemiologist Kamiliny Kalahne said outbreaks usually spread in areas where hospitals have poor infection control and limited access to resources such as running water.

"People who become sick with it almost always know how they got sick: because they looked after someone in their family who was very sick -- who had diarrhea, vomiting and bleeding -- or because they were health staff who had a lot of contact with a sick patient," she said.

Can it live outside a host?

MSF says that while the virus is believed to be able to survive for some days in liquid outside an infected organism, chlorine disinfection, heat, direct sunlight, soaps and detergents can kill it.

Can it travel through the air, like a common cold or the flu?

"This is not an airborne transmission," said Dr. Marty Cetron, director of CDC's Division of Global Migration and Quarantine. "There needs to be direct contact frequently with body fluids or blood."

What about planes? Can fellow passengers become infected if someone on the flight has the virus? Could Ebola spread around the world via air travel?

While the CDC acknowledges it's possible a person infected with Ebola in West Africa could get on a plane and arrive in another country, the chances of the virus spreading during the journey are low.

"The Ebola virus spreads through direct contact with the blood, secretions, or other body fluids of ill people, and indirect contact -- for example with needles and other things that may be contaminated with these fluids."

Travelers should take precautions by avoiding areas experiencing outbreaks and avoid contact with Ebola patients.

"In the rare event that a person infected with the Ebola virus was unknowingly transported by air, WHO advises that the risks to other passengers are low.Nonetheless, WHO does advise public health authorities to carry outcontact tracing in such instances."

Is Ebola going to be our era's plague or Black Death? Is it the most dangerous disease on the planet?

Not likely, says Gupta.

"Ebola is not the great plague; there's no question about that," he explained. "The grim reality is that it often kills so quickly that people don't have time to spread it."

"It's a myth that Ebola is the most dangerous disease that humans have ever encountered," he added. "HIV/AIDS, for example, certainly has killed more people, and up until recently, there was no treatment for that disease either. Rabies, something that you can get from animals as well, if you develop symptoms, you're very unlikely to survive. With Ebola right now, about seven out of 10 people are dying (in Guinea), but not everybody."

Doctors believe surviving Ebola leaves you immune to future infection. Scientists have found that people who survive Ebola have antibodies in their blood that would provide protection against that strain of the virus in the future, and possibly against other strains as well.

But, as you can imagine, they haven't tested this theory by infecting survivors with the virus again.

How do people react to Ebola survivors?

CNN's Nima Elbagir, who has been reporting on the outbreak in West Africa, says those "lucky" enough to survive the disease frequently find that the stigma attached to Ebola means they are ostracized once they recover.

"They find it very difficult to come back to their communities and be accepted, because people just don't believe that they have been cured," she explains.

"There's a lot of superstition, a belief that Ebola is almost a 'curse' and that makes it much more difficult to deal with."

Where did Ebola start?

The WHO says it is believed that fruit bats may be the natural host of the Ebola virus in Africa, passing on the virus to other animals.